Hydraulic clamp system for guillotine cutters



June 8, 1965 c. THUMIM 3,187,508

HYDRAULIC CLAMP SYSTEM FOR GUILLOI'INE CUTTERS Filed June 29, 1964 1 2 Sheets-Sheet 1 PRESS .74. XIV/FA 6' 4/1/7701 F?! 6' 51/176 way:

June 8, 1965 C. THUMIM HYDRAULIC CLAMP SYSTEM FOR GUILLOTINE CUTTERS Filed June 29, 1964 2 Sheets-Sheet 2 United States Patent 3,187,503 HYDRAULIQ CLAMP SYSTEM FOR GIHLLOTENE CUTTERS Carl Thurnim, hicago, IlL, assignor to Miehle-Goss- Dexter, Incorporated, Chicago, EL, a corporation of Delaware Filed June 29, 1964, Ser. No. 378,593 12 Claims. (Cl. 60-52) This invention relates to guillotine type paper cutting machines and more particularly to machines which use a hydraulically operated clamp.

It is an object of the invention to provide a hydraulically operated clamp capable of rapid descent to the point of contact with a paper pile followed by subsequent heavy pressure application to the pile.

It is a further object of the invention to provide a system in which maintaining the clamp in upper or idle position requires a minimum of power.

It is a further object of the invention to provide a system wherein a relatively small control valve for the clamp power cylinder may be used.

It is yet another object of the invention to provide a system wherein the clamp will be maintained in upper position even when machine power is turned off.

Other objects and features of the invention will be I apparent from the description to follow.

Briefly, the system utilizes two pumps operating in parallel for pumping oil to the hydraulic cylinder which actuates the clamp. One such pump has approximately ten times the pumping capacity of the other and both pumps are utilized when the clamp is moving downwardly in order to effect rapid descent in conjunction with a prefill valve. However, when the clamp reaches the paper pile, a very high pressure is built up due to closure of the prefill valve responsive to engagement of the clamp with the paper pile while the continued pumping of oil from both pumps causes a rapid high pressure rise for clamping purposes. On the return or upward stroke of the clamp, both pumps are again operative until the clamp reaches its uppermost position at which time only the smaller pump remains operative to hold the clamp in that position, the larger pump then bypassing to a reservoir until another cutting cycle is initiated.

Other objects and features will be apparent from the detailed description of the invention which now follow in conjunction with the appended drawings in which:

FEGURE 1 shows a schematic view of the hydraulic system and the essential components.

FIGURE 2 is a line diagram of the hydraulic system.

Referring to FIGURE 1, there is shown therein a tank 10 supplying oil through filter 12 to two parallelly connected pumps 15 and 18 to feed oil into the system. Pump 18 is the larger of the two pumps and has approximately ten times the capacity of the smaller pump 15.

The clamp of the cutting machine (not shown), is operated by bell crank lever 22 pivotally connected by piston rod 25, actuated by pressure in rockable cylinder 28 which is of conventional construction.

Chamber so of the cylinder is connected with the tank 10 by means of the dump and prefill check valve 32 through pipe 38. A spring biased piston 39, normally in raised position as shown, will move down and maintain prefill valve 32 open when the clamp is being moved up by pressure from pumps 15 and 18 to exhaust chamber 30 to the tank. The area of piston 39 is about onefifth that of valve 32, so that the valve will remain closed when pressures in chamber 39 and pipe 35a are equal. The pipe 35 connects to the chamber 48. The chamber 30 is additionally connected to the tank through tubes 42 and 44, via four-way valve 46, which is solenoid operated as Patented June 8, 1955 ice by solenoid 47. Cylinder space 48 is connected to the pumps 15 and 18 via piping 50: Piloted check valve 60, check valve 58, four-way valve 46, and check valves 55 and 8t).

Four-way valve 46 controls operation of the upward and downward motion of the clamp in a conventional manner as by associated control circuitry, not shown.

A tube 62 connects to a pressure operated pilot piston device 65 from a point between the small pump 15 and check valve 55. Check valve X with a leak by-pass is provided in line 62 to maintain pressure on the pilot valve 65 when the pressure in 50 fluctuates during an operating cycle. The leak is provided to release pressure in tube 62 and permit closing of the piloted valve when the small pump stops. Another check valve Y is provided connected between the large pump 18 to line 50 to provide pilot pressure from that pump in case the small pump 15 driving linkage fails. A knife control pressure switch 66 is connected in piping 50 between the four-way valve 46 and check valve 55.

Piping 50 is connected by tube 68 to remote control valve 70, which, in turn, is connected by tube '73 to relief valve 75, which is connected to the tank by pipe '78. Valve 70 controls clamp pressure and is variable through the entire range in this case from 100-1000 p.s.i.; valve opens at the top setting of valve 70 to limit the maximum pressure of the system.

The relief valve 75 is connected via pipe 77 to piping 59, which connects through check valve 80 with pipe 35. Pipe 35 connects through a two-way valve 83 operated by solenoid 85 to the tank 10. The valve 83 is closed to tank 10 when solenoid 85 i energized, which occurs when the clamp is operating. Solenoid 85 is controlled by limit switch 87 maintained open by the clamp (not shown), in idle top position, so that pump 18 bypasses to the tank at that time. The check valve 58 is shunted by a flow control needle valve 88, which controls the rate of descent of the clamp by restricting flow from chamber 48 back to the tank as chamber 30 is filling.

A normally closed switch which may be part of the circuitry (not shown), is opened at the end of the cutting stroke to deenergize solenoid 47. Valve 46 is normally maintained in clamp up position as by a spring (not shown), in a conventional manner when solenoid 47 is deenergized.

Operation Assume, initially, the cutter is standing idle: The pumps are operating, the valve 46 is in up position and all control circuits (not shown), are deenergized. Two-way valve 83 is open and the oil from the large pump 18 bypasses through pipe 86 into the tank 10. The power for pump 18 used at this time consists of what is required to circulate the oil without any more pressure than is necessary to overcome the friction in the lines. At the same time, the small pump 15 is pumping oil through the check valve 55, through four-way valve 46, through check valves 58 and 60 into the cylinder chamber 48 which holds the clamp in the inactive top position. The pressure is maintained at a set figure by the relief valve 75, which drains into the tank 10 through tube '78. The clamp pressure adjusting valve '70 is equally pressurized at both ends at this time and does not function.

When the cutting operation is to take place, valve 46 is shifted to down position, as shown by the dotted lines, both solenoids 47 and 85 are energized by associated circuitry (not shown), of a conventional nature and twoway valve 53 is closed. Pump 15 forces oil through tube 62 and check valve X to pilot device 65 to hold open the check valve 69. Chamber 4% is connected through flow control needle valve 88 to valve 46 to tube 44 which empties into the tank. The clamp then starts to drop from its elevated position of its own weight and pulls in oil through prefill valve 32. At the same time, both pumps are pumping oil through valve 46 to pipe 42; into the chamber 30, check valves 55 and tit opening in the direction of flow. When the clamp reaches the paper, prefill valve 32 closes due both to the absence of suction in chamber 30, since the piston motion stops, and also due to pressure buildup of oil coming from the pumps. The pressure then rises very rapidly which causes the knife control pressure switch 66 to start cutting motion of the knife.

When the knife has finished its cutting cycle, the solenoid 47 is deenergized to permit shift of valve 46 to the clamp up position and solenoid 85 is kept energized during the full upward stroke of the clamp to maintain valve 83 closed. Thus, both pumps are pushing a large volume of oil into space 48 to move the clamp up rapidly. When the clamp reaches the top position, it strikes a limit switch 87, which deenergizes the solenoid 85, thus venting the large pump to the tank and the static position is reestablished, pump 15 maintaining the clamp in upper position.

As the clamp moves down, tube 68 is connected to pipe 44 via valve 46 and, thus, the regulating pressure valve 70 becomes effective. However, when the clamp moves up, the valve '70 is ineffective as previously mentioned and full pressure controlled by valve 75 is provided for the upward motion and this full pressure is maintained while the clamp is in the top position, the pressure being supplied by pump 15 only and, thus, the loss of energy is comparatively small.

Also, when the clamp moves up, the pressure from the small pump 15 is transmitted through tube 35 to small piston 39 which pushes valve 32 to open. Thus, the large oil volume in space 3% is exhausted into the tank through the prefill system. This permits valve 46 to be comparatively small, since only a portion of the oil exhausts through pipes 42, 44 and 50.

When the power of the machine is completely turned off and the motor stops, the pressure in tube 62 approaches zero and pilot 65 then permits check valve 60 to close. The oil in space 48 is therefore trapped and will tend to maintain the clamp in a top position indefinitely, assuming that the packings and the check valve surface do not permit oil to leak. 1

When it is desirable to raise the clamp very slowly as when changing knives, switch 87 can be opened manually so that only the small pump is providing upward pressure. 7.

Although I have described preferred embodiments of my invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

I claim:

1. A hydraulic system for the clamp of a paper cutter comprising a cylinder having a double-faced piston for effecting lowering and raising of a clamp, said cylinder having a chamber on each side of said piston, a prefill valve disposed for oil passage to and from one of said chambers, an oil tank having a passage to said prefill valve, a pair of pumps having intakes connected to said tank, and means whereby said one chamber is filled by oil from both of said pumps and by oil through said prefill valve when said clamp is descending, and means whereby said' pumps provide oil to the other of said chambers to raise said clamp, and means whereby one of said pumps is bypassed so as to be ineffective when said clamp has reached a predetermined upper position.

2. A system as set forth in claim ll, one of said pumps having a larger capacity than the other of said pumps,

the other. of said pumps effecting the holding of said clamp in said upper position.

3. In the system as set forth in claim 2, means for maintaining said prefill valve open to said tank when said clamp is rising, comprising a connection to one of said pumps and a pressure operated piston actuatable by oil pressure through said connection to maintain said prefill valve open, and an operator control valve for effecting control of fluid flow to and from said cylinder chambers wherein said one chamber exhausts a substantially greater portion of oil'therefrom through said prefill valve than through said control valve.

4. A hydraulic system for the clamp of a paper cutter comprising a cylinder having a double-faced piston for effecting lowering and raising of a clamp, said cylinder having a chamber on each side of said piston, a prefill valve disposed for oil passage to and from one of said chambers, an oil tank having a passage to said prefill valve, a pair of pumps, valve means whereby the outlets of said pumps are connected in parallel to fill either of said chambers for up or down clamp movement, wherein said one chamber is filled by oil from both of said pumps and by oil through said prefill valve when said clamp is descending, and means whereby one of said pumps is bypassed so as to be ineffective when said clamp has reached an upper position.

5. in a system as set forth in claim 4, one of said pumps having a larger capacity than the other of said pumps, the other of said pumps effecting the holding of said clamp in said upper position.

6. In a system as set forth in claim 5, and check valve means to trap oil in said other pump when said clamp is in upper position to hold said clamp in said position when said other pump is in non-operating condition.

7. A hydraulic system for the clamp of a paper cutter comprising a cylinder having a double-faced piston for effecting lowering and raising of a clamp, said cylinder having a chamber on each side of said piston, a prefill valve disposed for oil passage to and from one of said chambers, an oil tank having a passage to said prefill valve, a air of pumps having intakes connected to said tank means whereby said pumps are connected in parallel to said one chamber, and means whereby said one chamber is filled by oil from both of said pumps and by oil through said prefill valve when said clamp is descending, and means whereby said pumps provide oil to the other of said chambers when said clamp is rising, and means whereby one of said pumps is bypassed to said tank so as to be ineffective when said clamp has reached a predetermined upper position.

8. In a system as set forth in claim 7, one of said pumps having a larger capacity than the other of said pumps, the other of said pumps effecting the holding of said clamp in said upper position.

9. A hydraulic system for the clamp of a paper cutter comprising a cylinder having a double-faced piston for effecting lowering and raising of a clamp, said cylinder having a chamber on each side of said piston, a prefill valve disposed for oil passage to and from one of said chambers, on oil tank having a passage to said prefill valve, a pair of pumps having intakes connected to said tank means whereby said pumps are connected in parallel to said one chamber or to the other of said chambers whereby said one chamber is filled by oil from both of said pumps and by oil through said prefill valve when said clamp is descending and whereby said pumps provide oil to the other of said chambers when clamp is rising, and means whereby one of said pumps is bypassed so as to be ineffective when said clamp has reached an upper position.

10. The system as set forth in claim 9, one of said pumps having a larger capacity than .the other of' said pumps, the other of said pumps effecting the holding of said clamp in said upper position.

11. A hydraulic system for the clamp of a paper cutter comprising a cylinder having a double-faced piston for effecting lowering and raising of a clamp, said cylinder having a chamber on each side of said piston, a prefill valve disposed for oil passage to and from one of said chambers, an oil tank having a passage to said prefill valve, a pair of pumps, means whereby said pumps are connected in parallel to said one chamber or to the other of said chambers, whereby said one chamber is filled by oil from both of said pumps and by oil through said prefill valve when said clamp is descending and whereby said pumps provide oil to the other of said chambers when said clamp is rising, and means whereby one of said pumps is bypassed so as to be ineffective when said clamp has reached an upper position, said one pump having arlarger capacity than the other of said pumps, the other of said pumps thus efiecting the holding of said clamp in said upper position.

12. In the system as set forth in claim 11, means for maintaining said prefill valve open to said tank when said clamp is rising comprising a connection to said smaller pump and a pressure operated piston actuatable by oil pressure through said connection and operative to maintain said prefill valve open, and an operator control valve for etfecting control of fluid flow to and from said cylinder chambers wherein said one chamber exhausts a substantially greater portion of oil therefrom through said prefill valve than through said control valve.

References Cited by the Examiner UNITED STATES PATENTS 1,899,678 2/33 Ernst et al. 6052 1,982,711 12/34 Vickers 60-52 2,051,052 8/36 Morgan 6052 2,373,167 4/45 Cherry et a1 6052 FOREIGN PATENTS 357,406 9/31 Great Britain.

JULIUS E. WEST, Primary Examiner. 

1. A HYDRAULIC SYSTEM FOR THE CLAMP OF A PAPER CUTTER COMPRISING A CYLINDER HAVING A DOUBLE-FACED PISTON FOR EFFECTING LOWERING AND RAISING OF CLAMP, SAID CYLINDER HAVING A CHAMBER ON EACH SIDE OF SAID PISTON, A PREFILL VALVE DISPOSED FOR OIL PASSAGE TO AND FROM ONE OF SAID CHAMBERS, AN OIL TANK HAVING A PASSAGE TO SAID PREFILL VALVE, A PAIR OF PUMPS HAVING INTAKES CONNECTED TO SAID TANK, AND MEANS WHEREBY SAID ONE CHAMBER IS FILLED BY OIL FROM BOTH OF SAID PUMPS AND BY OIL THROUGH SAID PREFILL VALVE WHEN SAID CLAMP IS DESCENDING, AND MEANS WHEREBY SAID PUMPS PROVIDE OIL TO THE OTHER OF SAID CHAMBERS TO RAISE SAID CLAMP, AND MEANS WHEREBY ONE 